ATR-FTIR spectroscopic characterization of coexisting carbonate surface complexes on hematite
Geochimica et Cosmochimica Acta
By: J.R. Bargar, J. D. Kubicki, R. Reitmeyer, and J.A. Davis
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Abstract
The speciation of carbonate adsorbed to hematite in air-equilibrated aqueous solutions has been studied using ATR-FTIR spectroscopy. Samples were measured over a range of pH conditions, at 0.1 M NaCl and at low ionic strength, and in H2O and D2O solutions to permit a multispecies analysis of the data. Second-derivative analyses and fits to the spectra indicate the presence of two major and two minor surface-bound carbonate species. The two major complexes coexist at near-neutral pH and low ionic strength. One of these two complexes is relatively sensitive to ionic strength, being displaced at 0.1 M NaCl, whereas the other is not. Comparison of experimental to DFT/MO-calculated frequencies suggest these two major species to be (a) a monodentate binuclear inner-sphere carbonate surface complex, and (b) a fully or partially solvated carbonate (CO32-) species that is symmetry broken and appears to reside in the structured vicinal water layers at the hematite-water interface, retained by hydrogen bonding and/or other forces. Minor carbonate complexes include diffuse layer CO32- and an unidentified inner-sphere species. Both of the dominant species observed here are likely to be significant controls of the surface charge and sorptive properties of Fe-oxides. Copyright ?? 2005 Elsevier Ltd.
Suggested Citation
Bargar, J., Kubicki, J.D., Reitmeyer, R., Davis, J., 2005, ATR-FTIR spectroscopic characterization of coexisting carbonate surface complexes on hematite: Geochimica et Cosmochimica Acta, v. 69, no. 6, p. 1527-1542, https://doi.org/10.1016/j.gca.2004.08.002.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | ATR-FTIR spectroscopic characterization of coexisting carbonate surface complexes on hematite |
| Series title | Geochimica et Cosmochimica Acta |
| DOI | 10.1016/j.gca.2004.08.002 |
| Volume | 69 |
| Issue | 6 |
| Year Published | 2005 |
| Language | English |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Geochimica et Cosmochimica Acta |
| First page | 1527 |
| Last page | 1542 |